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Did I find a fossil egg or turtle shell?

Many fossil eggs and turtle shells are reported in Kentucky. None (so far) have turned out to be fossil eggs or turtle shells. Although it is possible that fossil eggs and turtle shells will someday be found in Kentucky, all of the misidentified fossils that have been reported are actually concretions or man-made objects.


nonturtle_concretion.jpg

Concretions are not fossils, but sometimes are confused with fossil eggs, turtle shells, and other bones.

Concretions are naturally occurring circular to oval-shaped mineral deposits in rock. Limestone concretions are very common in Pennsylvanian-age strata of the Eastern and Western Kentucky Coal Fields. These concretions can be more than five feet in diameter. They are commonly gray to tan in color, although small concretions may be encased in coal, and shiny black in color. Sometimes the outer surface of concretions are cracked into polygonal patterns or concentric lines that may have the appearance of growth lines on a turtle shell. Siderite is another type of mineral that forms concretions. It is common throughout Kentucky. Generally siderite forms red, orange, or brown concretions, from inches to a foot in length. Some concretions are oval to circular. Others have irregular shapes that may look like horns, teeth, or claws. Siderite concretions sometimes fill the voids left by burrowing organisms, called trace fossils. Geodes are another type of circular to oval-shaped rock. These are mostly formed from concretions of quartz. Sometimes crystals form inside the concretions. Geodes are common in some Mississippian-age strata.


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Some man-made objects are also misidentified as fossil eggs. Circular to oval ceramic balls have periodically been found in creeks and soil in central and eastern Kentucky. Some were used in large vats for mixing paints. Others were used for grinding purposes. One of the clues you can use to determine if an object you find is one of these ceramic balls is to feel the weight of the object in your hand. Does it feel heavy? Possibly, heavier than it should? These ceramic balls were made with barite, which is very dense, so the balls are usually heavy. Also, because they are ceramic, they may feel cold or warm to the touch. Ceramics hold in the temperature of their surroundings well.


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Fossil dinosaur eggs have never been found in Kentucky and are unlikely to ever be found here. Only far western Kentucky, in the Jackson Purchase, has strata of the right age to yield dinosaur fossils. The image above shows what dinosaur eggs look like. The only fossil dinosaur eggs that have been found in North America, are found in the west. They are never found as isolated fossils, but are found in nesting sites, with many eggs arranged in distinct patterns.